The present invention relates to a disposable surgical safety scalpel for medical use, having a retractable blade.
A scalpel is a highly professional surgical instrument which has been perfected over the years to such an extent that it cannot be compared to a jack knife or a cutter.
In describing the prior art, reference can be made only from an historical viewpoint to some patents relating to knives described in the more or less recent past, whose characteristic was to have a blade that is positioned after use in a protective container.
This is the case, for example, of the following patents:
GB- 5487 (LAKE), which as far back as 1884 described a knife with an extractable blade;
U.S. Pat. No. 4,028,758 (O""CONNOR), which describes a combination of a utility knife and a staple remover;
U.K.-1511889 (STEABBEN), which describes a pocket cutter with a blade that retracts but not automatically;
U.S. Pat. No. 4,769,912 (DAVIS), which describes a knife with an acceleration sensor;
U.S. Pat. No. 4,858,320 (LEMAIRE), which describes a pocket knife with retractable blade;
DE-3735294 (TEIHS), U.S. Pat. No. 4,835,865 (KNOOP) and lastly BE.1.002.554 (VAN HOOYDONCK), which describe an industrial cutter with retractable blade.
As it is well known, the surgical scalpels existing on the market are of the disposable or reusable type, with a fixed or interchangeable blade, and do not normally have any protection, except for a blade protecting cap in the case of disposable scalpels, which cap is slipped off before use and could be replaced after use.
In fact the cap should never be replaced because this maneuver can cause unwelcome cuts, with the risk of transmission of diseases, including serious ones like AIDS and viral hepatitis.
The use of a barrier system, such as gloves with a steel mesh, which protect from cuts but not from stab wounds, is not well accepted because of the increased thickness and stiffness of the gloves, which leads to a loss of sensitivity.
The use of a different system, called xe2x80x9cMagnetic Drapexe2x80x9d, which consists of a sort of magnet cloth to be placed near the operating field and to which the surgical instruments adhere through the action of a magnet, avoids the stage of passing the instruments from hand to hand, thus eliminating some wounds, i.e. those that occur during exchange of instruments between operators.
This system is poorly received by surgeons because it is essential to look away from the operating field to grasp the instrument and also because it is of no use for non-metallic objects.
The majority of accidental scalpel stab wounds or cuts occurs not so much when the surgeon makes an incision in the patient""s skin or tissue as when the scalpel is passed from hand to hand by the medical operators or during disposal.
A study published in the USA in April 1995 by Dr. Janine Jagger in xe2x80x9cAdvances in exposure preventionxe2x80x9d, Volume 1 No. 3 published by xe2x80x9cINTERNATIONAL HEALTH CARE WORKER SAFETY RESEARCH AND RESOURCE CENTERxe2x80x9d showed that 34% of scalpel wounds occur during use of the instrument, whilst the remaining 39% and 27% , respectively, take place when the scalpel is passed from hand to hand by operators and during removal replacement-disposal of the blade.
From these data it emerges that, overall, scalpels with an exposed blade or an interchangeable blade are responsible for 66% of cut wounds that occur among medical operators before, during and after use of the instrument.
It is for this reason that all scalpels with an exposed blade, such as those currently on the market, must be considered dangerous, as well as those with an interchangeable blade, such as those forming the object of the following patents:
PCT-WO 90/11725 (DOLGIN), which describes a metal scalpel with a mobile guard, with no automatic return and requiring replacement of the blade;
U.S. Pat. No. 5,250,063 (ABIDIN), which describes a metal scalpel with a mobile guard and an interchangeable blade;
PCT-WO 94/13216 (WERNER), which describes a metal scalpel with a voluntarily and automatically retracting blade that is extremely dangerous in that, pressure exerted on the rear part causes an accidental forward movement of the blade, is difficult to construct and also has an interchangeable blade;
PCT-WO 95/15723 (GHARIBIAN), which describes a scalpel with a mobile guard and interchangeable blade without any locking system between the cap and the blade holder, making it difficult to use and dangerous;
PCT-WO 93/24064 (NEWMAN P. H.) and U.S. Pat. No. 5,403,337 (PLATTS) which describe a disposable scalpel with a blade that can be changed during the surgical procedure, without foreseeing any protection for used blades.
Changing of the blade is in fact the weak point of any instrument, even those considered safe, because handling necessarily leads to an increased risk of accidental wounds.
In the analysis of the prior art it can be seen that as time went on, inventors refined the idea of a safe scalpel to meet the need for protection required by surgeons.
Starting from mobile blade protection system without automatic return, such as, for example, those described in patents:
U.S. Pat. No. 3,905,101 (SHEPHERD), U.S. Pat. No. 3,906,626 (RIULI), U.S. Pat. No. 4,414,974 (DOTSON), EP-0 251 485 (GORDY), U.S. Pat. No. 4,735,202 (WILLIAMS), EP-0 612 506 (NEWMAN C. D.), whose main defects lie in the need to use both hands to set up or to protect the instrument and the necessity to remember to cover the blade each time it is passed from hand to hand, systems have been designed with a mobile blade guard that can be moved with only one hand, but still without automatic return of the cap, such as those described in patents:
PCT-WO 90/11725 (DOLGIN), U.S. Pat. No. 5,250,063 (ABIDIN), U.S. Pat. No. 5,417,704 (WONDERLEY), PCT-WO 95/15723 (GHARIBIAN), in which advancement and retraction of the protective cap is carried out with one hand and must be intentional on the part of the operator.
Again with regard to mobile guard, the following patents must be considered separately:
U.S. Pat. No. 5,330,492 (HAUGEN), which describes a scalpel with a guard that can be moved by means of a push-button, which when pressed causes the protective cap to retract, uncovering the blade, and when released unintentionally causes the opposite effect; this instrument must be grasped in a an unnatural way, does not offer guarantees of safety because the push-button protrudes excessively and in addition, because of its excessive height, does not allow a correct cutting angle on the skin surface;
U.S. Pat. No. 5,330,494 (VAN DER WESTHUIZEN), which describes a guard that can move transversely to the blade, constituting a danger not only for the operators, because pressure exerted-casually on the lower edge of the cap causes uncovering of the blade with a high risk of wounds, but also for patients, since the cutting force cannot be regulated.
More recently different systems have been proposed, such as, for example, that in U.S. Pat. No. 5,116,351 (FRASSETTI), which describes a mobile blade mechanism, with automatic return of the blade to the protected position and with the possibility of voluntary locking, but it is basically awkward, because it obliges the operator to work in an unnatural position, that is with the finger exerting a certain pressure on the upper edge of the blade and with the blade partly covered by the protection system;
and that of U.S. Pat. No. 5,207,696 (MATWIJCOW), which describes a scalpel with a retractable blade and mobile guard, but which seems too bulky and therefore awkward and has no automatic involuntary return of the blade to the covered position.
A further development in the design of these instruments has come about with a concept that foresees the possibility of extracting the blade from the handle. This is probably the idea that holds most advantages, because it offers interesting solutions to the problems described up to now, although each of the ideas proposed gives rise to some considerations as regards their practical operation.
A first proposal for a retractable blade is presented in:
EP-0 217 638 (DESATNICK), which describes an instrument for closed cavity surgery, with a small retractable blade, without automatic return, not disposable, therefore dangerous during blade changes, and not suitable for skin incisions;
PCT-WO 93/24064 (NEWMAN P. H.), which describes a scalpel with locking of the exposed blade, which is very difficult to set up, with voluntary return, with the risk of the blade holder with the blade coming out accidentally from the rear part of the cover, without any protection against an accidental forward movement of the blade and with the possibility of replacing the blades during a surgical procedure, an operation which seems dangerous because the exposed blade is handled;
U.S. Pat. No. 5,330,493 (HAINING) which describes a disposable scalpel with a retractable blade, without automatic return of the blade to the resting position, with a button for forward movement of the blade that is situated on its upper edge and is therefore awkward to slide, and with a permanent end-of-use lock, which seems superfluous and could sometimes be applied accidentally, thus making it impossible to use the instrument;
PCT-WO-94/13216 (WERNER), which describes a metal scalpel with voluntary automatic retraction of the blade that is extremely dangerous because a pressure exerted on its rear part causes an accidental unintentional forward movement of the blade. Said metal scalpel is difficult to construct and furthermore has an interchangeable blade;
U.S. Pat. No. 5,344,424 (ROBERTS) which presents a disposable scalpel with voluntary retraction, with three locking positions, i.e. an operative or set up position, an inoperative position and a safety position, where the only innovation appears to be the internal safety device, but which is difficult to handle and dangerous because the blade advance system protrudes too far;
U.S. Pat. No. 5,531,754 (SHACKELFORD), which presents a scalpel with voluntary retraction, but dangerous because the blade advance system protrudes too high;
EP-0 622 047 (DERBYSHIRE), which describes an original blade advance system in which pressure is exerted on a flexible container (balloon), with automatic spring-operated return, with the defect that seeing the blade retract each time, pressure is exerted on skin or tissues because of the intrinsic elasticity of the balloon itself, and the blade can accidentally move forward through unintentional pressure exerted by other instruments or hands;
U.S. Pat. No. 5,403,337 (PLATTS), which describes a scalpel wholly similar to the one described in PCT-WO 93/24064 (EWMAN P. H.), criticizing it as awkward and dangerous and adding its own small modification to eliminate these defects, but making it more difficult to set up with only one hand (the rear part of the handle has been widened to allow for positioning of two stops) and still foreseeing blade changes during the surgical procedure, which continues to represent a hazard;
U.S. Pat. No. 5,431,672 (COTE), which presents a scalpel with automatic, voluntary return of the blade with an additional internal lock, which could be accidentally applied during surgical procedures, forcing the medical staff to use a new scalpel;
PCT-WO-95/24855 (DILLON), which shows a scalpel with automatic, voluntary blade return, with an unsafe stopping system for the exposed blade and with locking devices not better identified to avoid re-use;
PCT-WO 93/25152 (FLUMENE et al.), which presents a disposable scalpel with rear lock to prevent any accidental forward movement of the blade, with easy blade exposure, without any locking in the operative or set up position of the blade, so as to have automatic, involuntary return and locking in the resting position; moreover, a particular characteristic is the possibility of graduating extraction of the blade according to the type of incision, always acting on the instrument in a comfortable, ergonomic position; the only drawback to be noted is that since it does not have a forward lock, use of this instrument is rather awkward in some operating conditions, so the presence of a stop device for the blade in operative position could be desirable in some circunstances;
U.S. Pat. No. 6,022,364 (FLUMENE et al.), which describes a disposable scalpel with the same features of PTC-WO 93/25152, but with a blade""s voluntary lock in position of use, which the operator can operate or not, depending on how he prefers to work. The scalpel has a further lock-safety-cover system, which operates at the end of a retraction stroke of the blade, thus avoiding an accidental emerging of the same.
The aim of this invention is, therefore, to solve some of the drawbacks posed by the prior art.
In particular, an aim of the invention is to provide a scalpel that is safe when passed among the operators, protected during transport and disposal of used materials, and to offer different possibilities of use, so that it is accepted by virtually all users, irrespective of their preferences for handling of the instrument.
Another aim of the invention is to provide safety locks for the blade that can easily be removed by moving one finger of the hand holding the scalpel, which is the same finger used to advance the blade.
Yet another aim of the invention is to provide a safety scalpel of the above type that is easy to make, automatically assemblable and economical.
A surgical safety scalpel in accordance with the invention is characterized by the characteristics listed in appended independent claim 1.
Essentially, the scalpel according to the invention is provided with a voluntary locking means for intentionally locking the blade in position for use, which the operator can operate or not, depending on how he prefers to work.
If this locking means is operated, it must be disabled after use to allow return of the blade.
However, this maneuver is extremely simple and does not require particular care on the part of the user.
An essential feature of the present invention lies in the presence of an automatic safety-cover system of the push-button of the blade, which automatically operates at the end of a retraction stroke of the blade, thus avoiding an unintentional driving of the push-button and therefore an accidental emerging of the blade.
An advantage of the present invention lies in the fact that the maneuvers made on the scalpel (retracting the push-button coverxe2x80x94advancing the bladexe2x80x94inserting and releasing the front lock of the blade when required) are effected by means of a single finger of a same hand, keeping the scalpel in its correct use position and leaving the other hand free to make another action.